The company said it would put Quarter Pounders back on the menu, without the raw onions that were considered the likely source of the bacteria. Food Contamination and Poisoning, E Coli (Bacteria), Beef, Fast Food Industry, Meat, Onions, McDonald’s Corporation, Taylor Farms, Colorado The company said it would put Quarter Pounders back on the menu, without the raw onions that were considered the likely source of the bacteria. NYT > Business